JP2005320496A - Water-borne coating composition and coating film formation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-borne coating composition which can express a flatting appearance and is excellent in followability to a substrate, and to provide a coating film formation method using the composition. <P>SOLUTION: This water-borne coating composition comprises a synthetic resin emulsion (I) having a glass transition temperature of -60 to 30°C, and a pigment (II) having a volume density of 25-80%. The pigment (II) contains an organic powder (a) comprising a polymer having a mean particle size of 0.1-100 μm and a glass transition temperature of -60 to 60°C and/or an organic powder (b) having a core portion comprising the polymer having the same particle size as above and the glass transition temperature of <30°C and a shell portion comprising the polymer having the glass transition temperature of ≥30°C. The pigment (II) is prepared so as to contain the powders (a) and/or (b) of ≥5 vol% based on the whole pigment component. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an aqueous coating composition that can exhibit a matte appearance and is excellent in followability to a base, and a coating film forming method using the aqueous coating composition.

2. Description of the Related Art Conventionally, buildings and civil engineering structures have been painted with various paints for the purpose of protecting the surface and improving aesthetics. Among these, a paint called a flat paint is widely used because it can form a coating film with a reduced surface gloss and can provide a calm finish. A typical example of the flat paint is a paint defined in JIS K5663 “Synthetic Resin Emulsion Paint”.
However, since a large amount of pigment is mixed in a flat paint, the formed coating film is usually hard. Therefore, it is not very suitable for a site where followability to the displacement of the ground is required.

On the other hand, Patent Document 1 (Japanese Patent Laid-Open No. 11-21514) discloses a water-based matte paint that can be applied on an elastic coating film. The paint described in the publication uses an emulsion of a carbonyl group-containing copolymer having a glass transition temperature of −30 to 15 ° C. as a binder, and the pigment volume concentration is adjusted to 25 to 40%.
However, in the water-based matte paint described in Patent Document 1, the pigment volume concentration has to be set low in order to ensure followability to the base, and a sufficient matte effect may not be obtained. Further, when the water-based matte paint of the publication is applied on an elastic coating, the coating of the water-based matte paint follows the displacement of the elastic coating if the elastic coating exceeds 150%. It is not possible to cause cracks and peeling. That is, the water-based matte paint described in Patent Document 1 has room for improvement in terms of the matte effect and the followability to the ground.

Japanese Patent Laid-Open No. 11-21514

  The present invention has been made in view of the above-described problems, and is capable of expressing a matte appearance and further being excellent in followability to a base, and uses the aqueous paint composition. The object is to obtain a coating film forming method.

  As a result of intensive studies to achieve the above object, the present inventor has conceived an aqueous coating composition using a specific organic powder as a matting agent, and has completed the present invention.

  That is, the present invention has the following characteristics.

An aqueous coating composition having a pigment volume concentration of 20 to 80% comprising a synthetic resin emulsion (I) having a glass transition temperature of −60 to 30 ° C. and a pigment (II), wherein the pigment (II) is:
Organic powder (a) made of a polymer having an average particle diameter of 0.1 to 100 μm and a glass transition temperature of −60 to 60 ° C. and / or an average particle diameter of 0.1 to 100 μm and a glass transition temperature Organic powder (b) having a core part made of a polymer of less than 30 ° C and a shell part made of a polymer having a glass transition temperature of 30 ° C or higher
Is contained in an amount of 5% by volume or more based on the total component (II).

As the pigment (II),
Inorganic powder (c) having an average particle size of 0.1 to 100 μm,
Organic powder having an average particle diameter of 0.1 to 100 μm (excluding those having a polymer having a glass transition temperature of 60 ° C. or lower) (d),
Hollow powder (e) having an average particle diameter of 0.1 to 100 μm,
At least one selected from
1. It is contained in a volume ratio of 95: 5 to 5:95 with respect to the total amount of the component (a) and / or the component (b). The aqueous coating composition as described.

As the pigment (II),
The inorganic powder (c-1) having an average particle diameter of 0.1 to 100 μm and a Mohs hardness of 7 or less is 95: 5 with respect to the total amount of the component (a) and / or the component (b). Included in a volume ratio of ˜5: 95. The aqueous coating composition as described.

  At least one of the components (c-1) is an inorganic powder (c-1 ′) having an average particle size of 0.5 to 50 μm and a Mohs hardness of 0.5 to 3.0, and the component (a) and 2./(b) The above component (c-1 ′) is contained in a volume ratio of 95: 5 to 5:95 with respect to the total amount of component 3. The water-based paint composition described in 1.

  The component (c) and / or the component (d) includes a powder having moisture absorption / release properties. ~ 4. The water-based coating composition according to any one of the above.

  The component (a) and / or the component (b) is contained in an amount of 30% by volume or more based on the total component (II). ~ 5. The water-based coating composition according to any one of the above.

  1. 1 to 100 parts by weight of a water-dispersible water repellent (III) is further contained in solid content with respect to 100 parts by weight of solid content of the synthetic resin emulsion (I) ~ 6. The water-based coating composition according to any one of the above.

  1. After applying a primer having an elongation of the formed coating film of 50% or more to the substrate, 1. ~ 7. A method for forming a coating film, comprising applying the aqueous coating composition according to any one of the above.

  For inorganic substrates or wood substrates: ~ 7. A method for forming a coating film, comprising applying the aqueous coating composition according to any one of the above.

  According to the present invention, it is possible to obtain a water-based coating composition that can exhibit a matte appearance and is excellent in followability to the groundwork.

  Hereinafter, the best mode for carrying out the present invention will be described.

In the aqueous coating composition of the present invention, a synthetic resin emulsion (hereinafter referred to as “component (I)”) having a glass transition temperature of −60 to 30 ° C. is used as a binder.
Specifically, as the component (I), for example, a vinyl acetate resin emulsion, a vinyl chloride resin emulsion, an epoxy resin emulsion, an acrylic resin emulsion, a urethane resin emulsion, an acrylic silicon resin emulsion, a fluororesin emulsion, or a composite system thereof. Can be mentioned. These can be used alone or in combination of two or more.

  Further, the component (I) may have crosslinking reactivity. When the component (I) is a crosslinking reaction type synthetic resin emulsion, the water resistance, weather resistance, adhesion and the like of the coating film can be improved. The crosslinking reaction type synthetic resin emulsion may be either one that causes a crosslinking reaction by itself or one that causes a crosslinking reaction by a separately mixed crosslinking agent. Such crosslinking reactivity includes, for example, carboxyl group and metal ion, carboxyl group and carbodiimide group, carboxyl group and epoxy group, carboxyl group and aziridine group, carboxyl group and oxazoline group, hydroxyl group and isocyanate group, carbonyl group and hydrazide group. It can be imparted by combining reactive functional groups such as epoxy groups and amino groups, aldo groups and semicarbazide groups, keto groups and semicarbazide groups, and alkoxyl groups.

  Although the manufacturing method of (I) component is not specifically limited, For example, emulsion polymerization, soap-free emulsion polymerization, dispersion polymerization, feed emulsion polymerization, feed dispersion polymerization, seed emulsion polymerization, seed dispersion polymerization, etc. are employable.

The glass transition temperature (hereinafter referred to as “Tg”) of the component (I) is usually set to −60 to 30 ° C., preferably −40 to 25 ° C., more preferably −30 to 20 ° C. When Tg is too high, followability to the ground becomes insufficient, and cracks are likely to occur in the coating film. When Tg is too low, contaminants tend to adhere to the coating surface, which is not practical. The Tg in the present invention is a value obtained from the formula of Fox from the type of monomer constituting the component (I) and its constituent ratio.
(I) The average particle diameter of a component is about 0.05-0.4 micrometer normally.

  In the present invention, a pigment (hereinafter referred to as “component (II)”) is mixed with the component (I). In the present invention, by using a specific powder as the component (II), it is possible to obtain a paint having both a matte effect and followability to the ground.

  The first component (II) is an organic powder (hereinafter referred to as “component (a)”) having an average particle size of 0.1 to 100 μm and comprising a polymer having a Tg of 60 to 60 ° C. (A) The average particle diameter of a component is 0.1-100 micrometers normally, Preferably it is 0.5-50 micrometers, More preferably, it is 1-30 micrometers.

  The polymer of component (a) is formed by copolymerizing various polymerizable monomers. Examples of polymerizable monomers that can be used include ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isononyl (meth) acrylate, and lauroyl. Examples include alkyl (meth) acrylate styrene such as (meth) acrylate and stearyl (meth) acrylate, aromatic vinyl monomers such as vinyltoluene and α-methylstyrene. A polyfunctional monomer having two or more vinyl groups in the molecule can also be used.

  (A) Tg of a component is -60-60 degreeC normally, Preferably it is -50-50 degreeC, More preferably, it is -40-40 degreeC. (A) Tg of a component can be adjusted by setting suitably the kind and ratio of the monomer which comprise a polymer. When Tg is too high, sufficient performance cannot be obtained in the followability to the base, and when Tg is too low, it is disadvantageous in terms of contamination resistance.

In the present invention, in place of the above (a), an organic powder having an average particle size of 0.1 to 100 μm and having a core part made of a polymer having a Tg of less than 30 ° C. and a shell part made of a polymer having a Tg of 30 ° C. or more. (Hereinafter referred to as “component (b)”) can be used. By using such a component (b), the matte effect and the followability to the ground can be further enhanced. In this case, the component (a) and the component (b) can be mixed and used.
(B) The average particle diameter of a component is 0.1-100 micrometers normally, Preferably it is 0.5-50 micrometers, More preferably, it is 1-30 micrometers.

(B) Tg of the core part of a component is usually less than 30 degreeC, Preferably it is -60-20 degreeC, More preferably, it is -60-10 degreeC. The Tg of the shell part is usually 30 ° C. or higher, preferably 50 to 140 ° C., more preferably 60 to 130 ° C.
In the component (b), as long as the Tg of the core part and the shell part is within a predetermined range, the monomer constituting the polymer is not particularly limited, and the same monomer as the component (a) is used. it can.
The component (a) and the component (b) are both non-film-forming powders and are different materials from the component (I) having film-forming properties.

  The mixing ratio of the component (a) and / or the component (b) is generally 5% by volume or more, preferably 10% by volume or more, more preferably 20% by volume or more, more preferably, based on the total of the component (II). 30% by volume or more. With such a mixing ratio, both the matting effect and the followability to the substrate can be sufficiently exhibited.

As the second component (II),
An inorganic powder having an average particle size of 0.1 to 100 μm (hereinafter referred to as “component (c)”),
Organic powder having an average particle diameter of 0.1 to 100 μm (excluding those having a polymer having a glass transition temperature of 60 ° C. or lower) (hereinafter referred to as “component (d)”),
A hollow powder having an average particle size of 0.1 to 100 μm (hereinafter referred to as “component (e)”),
At least one selected from the group consisting of:

  Among the above-mentioned components, when the component (c) is used, the concealability of the formed coating film, matting effect, strength, wall thickness, workability at the time of coating, etc. can be improved. It is advantageous. The apparent specific gravity (hereinafter simply referred to as “specific gravity”) of the component (c) is usually 1 to 5.

As the component (c), an inorganic powder (hereinafter referred to as “component (c-1)”) having an average particle diameter of 0.1 to 100 μm and a Mohs hardness of 7 or less is preferable. In the present invention, an inorganic powder having such particle diameter and hardness characteristics is combined with the above-described component (a) and / or component (b) to obtain excellent physical properties in the followability to the ground. Can do. The Mohs hardness in the present invention is a value measured using a Mohs hardness meter (where diamond is 10).
As the component (c-1), one or more inorganic powders having an average particle diameter and a Mohs hardness within the above ranges can be used. In the present invention, at least one component (c-1) is used. However, an inorganic powder having an average particle diameter of 0.5 to 50 μm and a Mohs hardness of 0.5 to 3.0 is more desirable.

  The component (c-1) is not particularly limited as long as the average particle diameter and the Mohs hardness are within a predetermined range, and a known inorganic powder can be used. Examples of the component (c-1) include talc, wax, diatomaceous earth, clay, kaolin, calcined clay, mica, iron oxide, calcium carbonate, barium sulfate, zinc oxide, dolomite, and titanium oxide. . Among these, scaly inorganic powders such as talc, clay, kaolin, and mica are preferable in terms of followability to the substrate.

  The oil absorption amount of the component (c-1) is usually 200 ml / 100 g or less, preferably 150 ml / 100 g or less, more preferably 100 ml / 100 g, still more preferably 80 ml / 100 g or less. When the oil absorption amount of the component (c-1) is too large, the followability to the ground may be insufficient.

  As the component (d), an organic powder having an average particle diameter of 0.1 to 100 μm (excluding those having a polymer having a glass transition temperature of 60 ° C. or lower) can be used. Since the component (d) is excellent in dispersibility in the paint, it is possible to reduce the amount of the dispersant added in the paint. The use of component (d) is also effective in terms of the matte effect of the formed coating film, thickness, crack prevention, chemical resistance, scratch resistance, and the like. (D) The specific gravity of a component is 0.8-2 normally.

  Examples of the component (d) include urethane beads, acrylic beads, polyethylene beads, polypropylene beads, polymethyl methacrylate beads, polystyrene beads, nylon beads, styrene acrylic beads, silicon beads, fluorine beads, cellulose beads, vinyl chloride beads, Examples include EVA beads. These can be used alone or in combination of two or more.

  (E) As a component, the hollow powder whose average particle diameter is 0.1-100 micrometers can be used. By using such a component (e), it is possible to improve the concealability, thickness, crack prevention, workability during coating, and the like of the formed coating film. The specific gravity of the component (e) is usually 0.01 or more and less than 0.8.

  Examples of the component (e) include hollow ceramic beads and hollow resin beads. Examples of the ceramic component constituting the hollow ceramic beads include sodium silicate glass, aluminum silicate glass, borosilicate soda glass, carbon, alumina, shirasu, obsidian and the like. Examples of the resin component constituting the hollow resin beads include acrylic resin, styrene resin, acrylic-styrene copolymer resin, acrylic-acrylonitrile copolymer resin, acrylic-styrene-acrylonitrile copolymer resin, acrylonitrile-methacrylonitrile copolymer resin, Examples thereof include acrylic-acrylonitrile-methacrylonitrile copolymer resins and vinylidene chloride-acrylonitrile copolymer resins. These can be used alone or in combination of two or more.

  In the present invention, a powder having moisture absorption / release properties (hereinafter referred to as “moisture absorption / release powder”) can also be used in the component (c) and / or the component (d). By using such moisture-absorbing / releasing powder, it is possible to form a coating film that does not impair the breathability and moisture permeability of the base material while ensuring followability to the substrate, and efficiently use the moisture in the base material. The swelling and peeling of the coating film can be sufficiently suppressed by the action of diffusing well outside. Therefore, when such a moisture-absorbing / releasing powder is included, it is possible to obtain a paint particularly suitable for coating an inorganic substrate (particularly a cement-based inorganic substrate) or a wooden substrate.

Examples of the hygroscopic powder include boehmite, silica gel, zeolite, sodium sulfate, alumina, allophane, diatomaceous earth, siliceous shale, sepiolite, attabargite, montmorillonite, zonolite, imogolite, Otani stone powder, activated clay, charcoal, bamboo charcoal, activated carbon Wood powder, shellfish powder, alginate beads, porous synthetic resin particles, and the like.
Such moisture-absorbing / releasing powder may exhibit the ability to adsorb various chemical substances in addition to the moisture-releasing performance. Specifically, the performance of adsorbing volatile organic compounds such as formaldehyde or the performance of suppressing exudation of spears, acupuncture and the like contained in the base can be expected.

  In order to improve the adsorption performance of the chemical substance, a chemical substance adsorbent may be used instead of the hygroscopic powder or in combination with the hygroscopic powder. Such a chemical substance adsorbent is an effective component for preventing adsorption and re-release of formaldehyde, ammonia, hydrogen sulfide, methyl mercaptan, trimethylamine, nicotine and the like. Examples of the chemical adsorbent include aluminum tripolyphosphate, aluminum dihydrogen phosphate, layered zirconium phosphate, layered titanium phosphate, layered hafnium phosphate, layered tin phosphate, layered phosphate polyamine intercalation compound, active zinc oxide, Examples thereof include hydrous magnesium silicate, hydrotalcite, and frypontite.

  In the present invention, a photocatalytic substance can also be used in the above-mentioned component (c). In particular, such a photocatalytic substance effectively works to prevent decomposition and re-release of chemical substances when used in combination with the above-described moisture-absorbing / releasing powder and chemical substance adsorbent. Examples of the photocatalytic substance include TiO2, ZnO, Bi2O3, BiVO4, SrTiO3, CdS, InP, InPb, GaP, GaAs, BaTiO3, BaTiO4, BaTi4O9, K2NbO3, Nb2O5, Fe2O3, Ta2O3, Ta3N5, S3, In addition to Cu 2 O, SiC, MoS 2, RuO 2, CeO 2 and the like, composites of these with metals, metal oxides, layered compounds, and the like can be given.

The components (c), (d), and (e) shown above are usually 95: 5 to 5:95, preferably 90, with respect to the total amount of the components (a) and / or (b). : 10 to 10:90, more preferably 80:20 to 20:80, and still more preferably 70:30 to 30:70 in a volume ratio ((a + b) :( c + d + e)). In order to sufficiently exhibit both the matte effect and the followability to the ground, it is desirable to use each component within such a range.
In addition, when (c-1 ') component is included as (c-1) component, the volume ratio of (c-1') component with respect to the total amount of (a) component and / or (b) component is the said range. It is desirable to prepare so as to be within.

  The pigment volume concentration of the composition of the present invention is usually 20 to 80%, preferably 30 to 70%, more preferably 40 to 65%, and further preferably 45 to 60%. When the pigment volume concentration is within such a range, a sufficient matting effect can be obtained. Furthermore, in this invention, since specific powder is used as (II) component, the followable | trackability to a foundation | substrate can also be ensured. When the pigment volume concentration is too high, the followability to the ground becomes insufficient, and cracks are likely to occur in the coating film. When the pigment volume concentration is too low, the matting effect is insufficient. As the component (II) other than the above components, for example, coloring pigments, aggregates, fibers and the like can be used.

  The pigment volume concentration in the present invention is a volume percentage of the component (II) contained in the dry coating film, and is a value calculated by the following formula. Since the component (III) described later has substantially no film-forming performance, it is excluded when calculating the pigment volume concentration.

<Formula> Pigment volume concentration (%) = [(cw / cρ) / {(aw / aρ) + (cw / cρ)}] × 100
(Wherein, aw represents the mixing weight of component (I), aρ represents the specific gravity of component (I), cw represents the mixing weight of component (II), and cρ represents the specific gravity of component (II).)

  The composition of the present invention may further contain a water-dispersed water repellent (hereinafter referred to as “component (III)”) in addition to the above components. In the present invention, the action of such a component (III) can enhance the water-blocking effect, moisture-permeable effect, etc. of the coating film while ensuring followability to the base, such as swelling and peeling of the coating film. Can be sufficiently suppressed. Therefore, when (III) component is included, the coating material suitable for the coating of an inorganic base material (especially cement-type inorganic base material) or a wooden base material is obtained. The form of component (III) is not particularly limited as long as it is dispersed in water, and may be either a forced emulsification type emulsion using a surfactant or a self-emulsification type emulsion.

  As the component (III), (p) a water-dispersed water repellent (hereinafter referred to as “(p) component”) having at least one functional group selected from an amino group, a carboxyl group, an epoxy, and a reactive silyl group. Is preferred. If such a (p) component is used, it becomes possible to exhibit performance, such as a water-impervious effect and a moisture-permeable effect, over a long period of time. Of these, when the component (p) has a reactive silyl group, the component (I) preferably has a reactive silyl group. When the component (p) has an amino group and / or a carboxyl group, the component (I) preferably has an epoxy group. When the component (p) has an epoxy group, the component (I) preferably has a carboxyl group and / or an amino group.

  The component (p) usually has units represented by the following formulas (1) and (2).

（式中、Ｒ１は同一または異なって、アルキル基、アリール基、アラルキル基を示し、Ｒ２はアルキレン基、オキシアルキレン基を示す。Ｘはアミノ基、カルボキシル基、エポキシ基、反応性シリル基を示す。ｍ，ｎは１以上の整数である。）

(In the formula, R1 is the same or different and represents an alkyl group, an aryl group or an aralkyl group, R2 represents an alkylene group or an oxyalkylene group, and X represents an amino group, a carboxyl group, an epoxy group or a reactive silyl group. M and n are integers of 1 or more.)

  The mixing ratio of the component (III) is usually 1 to 100 parts by weight, preferably 2 to 50 parts by weight, more preferably 3 to 30 parts by weight in terms of the solid content with respect to 100 parts by weight of the solid content of the component (I). is there.

In the composition of the present invention, in addition to the above-described components, components that can be used in ordinary paints can also be included. Such components include, for example, thickeners, film-forming aids, leveling agents, wetting agents, plasticizers, antifreeze agents, pH adjusters, antiseptics, antifungal agents, antialgae agents, antibacterial agents, adsorption An agent, a dispersant, an antifoaming agent, an ultraviolet absorber, an antioxidant, a catalyst, a crosslinking agent, and the like can be used. Among these, as the adsorbent, for example, amine compounds, urea compounds, amide compounds, imide compounds, hydrazide compounds, azole compounds, azine compounds and the like can be used.
The composition of the present invention can be produced by uniformly mixing the above components by a conventional method. The composition of the present invention is usually used as a colored paint, but can also be used as a clear paint.

  The composition of the present invention can be suitably used as a surface finishing material (coating material) mainly in buildings, civil engineering structures and the like. Although the base material used as the object of coating is not specifically limited, An inorganic base material or a wooden base material is suitable.

  As the inorganic substrate, a cement-based inorganic substrate is particularly suitable. When the composition of the present invention is coated on a cement-based inorganic base material, the effects of the present invention can be sufficiently exerted. Such a cement-based inorganic base material is a material obtained by using cement as an essential component. As components other than cement, for example, aggregates such as silica sand, silica stone, and fly ash, fibers such as pulp and glass wool, and the like may be included.

  Specifically, examples of the cement-based inorganic base material include concrete, mortar, fiber-mixed cement board, cement calcium silicate board, slag cement pearlite board, asbestos cement board, ALC board, and siding board. Among these, base materials such as concrete and mortar are usually obtained by curing a material kneaded with water or the like at a construction site. Inorganic building materials such as ALC plates and siding plates are formed into plates by various methods such as papermaking, extrusion, and casting. The surface of these base materials may have been subjected to some surface treatment (for example, a sealer, a surfacer, a putty, a filler, etc.), or may have already been formed with a coating film.

  Examples of the wood base material include beech, cypress, too much, artificial materials such as teak and lauan, laminated wood / laminate, ordinary plywood, wood fiberboard / particle board, and the like. These may be flame retardant treated. Moreover, the surface of the base material may have been subjected to some surface treatment (for example, a sealer, a surfacer, a putty, a filler, etc.), or a coating film may be already formed.

  When the composition of the present invention is painted at a construction site or the like, it can be applied regardless of whether it is a new construction or a renovation. The plate-shaped building material can be coated before being brought into a construction site or the like (that is, during or after the building material is molded). It can also be applied to partial repairs.

Before applying the composition of the present invention, any primer can be applied.
In this case, as the undercoat material, an undercoat material having an elongation percentage of the formed coating film of 50% or more (preferably 100% or more, more preferably 150% or more) is suitable. By using such an undercoat material, sufficient performance can be ensured in terms of adhesion to a substrate, efflorescence prevention effect, and the like. Furthermore, the composition of the present invention can exhibit sufficient followability to such an elastic primer. The elongation percentage in the present invention is a value measured by “elongation test at 20 ° C.” of JIS A6909: 2003 7.29 “elongation test”.

Such an undercoating material usually contains a synthetic resin emulsion as an essential component, and further contains a filler, various additives and the like as necessary. A main material of a multi-layer finish coating material defined in JIS A6909 can also be used as a primer for the present invention.
The kind of the synthetic resin emulsion in the primer is not particularly limited, and for example, vinyl acetate resin, acrylic resin, vinyl chloride resin, epoxy resin, urethane resin, acrylic silicon resin, and the like can be used. These may have crosslinking reactivity. The Tg of the synthetic resin emulsion is usually −60 to 30 ° C., preferably −50 to 10 ° C.

  As the filler, heavy calcium carbonate, kaolin, diatomaceous earth, white carbon, clay, talc, barite powder, precipitated barium sulfate, barium carbonate, silica sand, wollastonite, mica and the like can be used. By mixing such a filler so that the pigment volume concentration is 20 to 70% (preferably 25 to 60%), a thick film type primer can be obtained, and various uneven patterns (sand walls) Pattern, stucco pattern, ripple pattern, yuzu skin pattern, lunar pattern, etc.) can be formed. In addition, such a thick film-type undercoat has an effect of reducing the displacement of the base material.

The undercoat material can be applied using, for example, a spray, a roller, a brush, a trowel, or the like. The painting may be performed in several times. It can also be diluted with water during painting. What is necessary is just to set the mixing amount of water suitably according to the coating instrument to be used, a desired coating surface shape, etc.
The coating amount of the primer is about 0.1 to 3 kg / m 2 (in the case of a thick film type, about 0.5 to 3 kg / m 2).

  The composition of the present invention may be applied after applying the primer as described above, or may be applied directly to the substrate. In painting the composition of the present invention, for example, a spray, a roller, a brush or the like can be used. The painting may be performed in several times. It can also be diluted with water during painting. The mixing amount of water may be appropriately set in consideration of the type of coating equipment, the state of the coating base, the temperature during coating, etc., but is usually about 0 to 20% by weight. The coating amount is usually about 0.1 to 0.5 kg / m2. Moreover, although the coating process and drying process of this invention composition should just normally be performed at normal temperature, it is also possible to heat. The drying time is usually about 0.5 to 4 hours at room temperature.

  Examples are given below to clarify the features of the present invention.

(Manufacture of paint)
According to the formulation shown in Table 1, paints were produced by mixing and stirring the respective raw materials by a conventional method. The following were used as raw materials.

Resin: Acrylic resin emulsion (methyl methacrylate-styrene-2-ethylhexyl acrylate-methacrylic acid copolymer, solid content 50% by weight, Tg-8 ° C.)
Inorganic powder 1: heavy calcium carbonate (average particle diameter 5 μm, Mohs hardness 3.0, oil absorption 28 ml / 100 g, specific gravity 2.7)
Inorganic powder 2: clay (average particle size 5 μm, Mohs hardness 1.5, oil absorption 32 ml / 100 g, specific gravity 2.6)
Inorganic powder 3: diatomaceous earth (average particle diameter 9 μm, Mohs hardness 1.0, oil absorption 170 ml / 100 g, specific gravity 2.3)
Inorganic powder 4: Titanium oxide (average particle size 0.2 μm, Mohs hardness 6.0, oil absorption 13 ml / 100 g, specific gravity 3.9)
Hollow powder: Acrylic resin hollow beads (average particle size 8 μm, Tg 105 ° C., specific gravity 0.5)
Organic powder 1: acrylic polymer powder (average particle size 8 μm, Tg 20 ° C., specific gravity 1.0)
Organic powder 2: Core-shell type acrylic polymer powder (average particle size 8 μm, core portion Tg-54 ° C., shell portion Tg 105 ° C., specific gravity 1.0)
Organic powder 3: acrylic polymer powder (average particle size 8 μm, Tg 105 ° C., specific gravity 1.0)
Water dispersion type water repellent: Emulsified dispersion of epoxy group-containing dimethylsiloxane compound, solid content 50 wt%
・ Dispersant: Polycarboxylic acid-based dispersant (solid content: 30% by weight)
・ Thickener: Hydroxyethylcellulose 3% by weight aqueous solution ・ Defoamer: Mineral oil-based defoamer

(Test method)
(1) Specular Glossiness Each paint is applied to one side of a glass plate (200 × 100 × 2 mm) using a film applicator with a clearance of 150 μm, and the coated surface is placed horizontally and in a standard state (temperature 23 ° C., relative humidity 50 %) For 48 hours to prepare a test specimen. The specular gloss (measurement angle 60 degrees) of the obtained specimen was measured with a specular gloss meter specified in JIS K5600-4-7: 1999. The evaluation criteria are as follows.
○: Mirror glossiness less than 5 △: Mirror glossiness of 5 or more and less than 10 ×: Mirror glossiness of 10 or more

(2) Repeatability of wet / cold heat resistance Main material (pigment volume concentration) of a waterproof synthetic resin emulsion-based multi-layer finishing coating material defined in JIS A6909: 2003 on a slate plate (150 × 70 × 3 mm) that has been previously sealed. 50%, elongation rate at 20 ° C (300%) was spray-coated at a coating amount of 2 kg / m2, dried for 24 hours in a standard state, and then each paint was spray-coated at a coating amount of 0.3 kg / m2 for testing. The body was made.
After curing for 14 days in the standard state, the prepared specimen was immersed in 23 ° C. water for 18 hours in accordance with JIS K 5660 6.14, and then immediately cooled in a thermostatic bath maintained at −20 ° C. for 3 hours. The mixture was heated for 3 hours in another thermostat kept at 50 ° C. After repeating this operation seven times, the sample was placed in a standard state for about 1 hour, and the state of the coating film surface was visually observed (in Table 1, expressed as “wet and cold-heat repeatability A”).
In addition, the test was conducted in the same manner as described above for the case where one cycle was 23 ° C. water for 18 hours, −20 ° C. for 3 hours, and 80 ° C. for 3 hours (in Table 1, “wet and cold heat repeatability B”). Notation).
The evaluation criteria are as follows.
A: No cracking or peeling occurred.
○: Almost no cracking or peeling occurred.
Δ: Partial cracking and peeling occurred.
X: Cracking and peeling occurred remarkably.

(Test results)
The test results are shown in Table 1. In Examples 1 to 7, a sufficient matte coating film was formed, and good results were obtained even in a wet and cold repeatability test.
In contrast, in Comparative Examples 1 to 3, the matting effect was insufficient. In Comparative Examples 4 to 6, sufficient results were not obtained in the wet / cool repeatability test.

Claims (9)

An aqueous coating composition having a pigment volume concentration of 20 to 80% comprising a synthetic resin emulsion (I) having a glass transition temperature of −60 to 30 ° C. and a pigment (II), wherein the pigment (II) is:
Organic powder (a) made of a polymer having an average particle diameter of 0.1 to 100 μm and a glass transition temperature of −60 to 60 ° C. and / or an average particle diameter of 0.1 to 100 μm and a glass transition temperature Organic powder (b) having a core part made of a polymer of less than 30 ° C and a shell part made of a polymer having a glass transition temperature of 30 ° C or higher
Is contained in an amount of 5% by volume or more based on the total component (II). As the pigment (II),
Inorganic powder (c) having an average particle size of 0.1 to 100 μm,
Organic powder having an average particle diameter of 0.1 to 100 μm (excluding those having a polymer having a glass transition temperature of 60 ° C. or lower) (d),
Hollow powder (e) having an average particle diameter of 0.1 to 100 μm,
At least one selected from
The water-based coating composition according to claim 1, wherein the composition is contained in a volume ratio of 95: 5 to 5:95 with respect to the total amount of the component (a) and / or the component (b). As the pigment (II),
The inorganic powder (c-1) having an average particle diameter of 0.1 to 100 μm and a Mohs hardness of 7 or less is 95: 5 with respect to the total amount of the component (a) and / or the component (b). The water-based coating composition according to claim 1, comprising a volume ratio of ˜5: 95.   At least one of the components (c-1) is an inorganic powder (c-1 ′) having an average particle size of 0.5 to 50 μm and a Mohs hardness of 0.5 to 3.0, and the component (a) and 4. The aqueous coating composition according to claim 3, wherein the component (c-1 ′) is contained in a volume ratio of 95: 5 to 5:95 with respect to the total amount of the component (b).   The water-based coating composition according to any one of claims 2 to 4, wherein the component (c) and / or the component (d) includes a powder having moisture absorption / release properties.   The aqueous coating composition according to any one of claims 1 to 5, wherein the component (a) and / or the component (b) is contained in an amount of 30% by volume or more based on the entire component (II).   The solid resin repellent (III) is further contained in an amount of 1 to 100 parts by weight in solid content with respect to 100 parts by weight in solid content of the synthetic resin emulsion (I). The aqueous coating composition as described.   The base coating material having an elongation percentage of the formed coating film of 50% or more is applied to the base material, and then the aqueous coating composition according to any one of claims 1 to 7 is applied as a top coating material. A method for forming a coating film.   A coating film forming method comprising applying the aqueous coating composition according to any one of claims 1 to 7 to an inorganic substrate or a wooden substrate.